1. Technical Field
The present disclosure relates to liquid crystal display devices (LCDs) and methods for driving the LCD devices, and particularly to an LCD device having a look up table for adjusting common voltages and a method for driving the same.
2. Description of Related Art
Because LCDs have the advantages of portability, low power consumption, and low radiation, they have been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras, and the like.
Referring to FIG. 4, a typical LCD 10 includes an LCD panel 11. The LCD panel 11 includes a pixel electrode 112, a common electrode 111, a liquid crystal layer 113, an upper polarizer 114, and a lower polarizer 115. The upper polarizer 114 is disposed opposite to the lower polarizer 115, and a polarizing axis of the upper polarizer 114 is perpendicular to that of the lower polarizer 115. The liquid crystal layer 113 is sandwiched between the upper polarizer 114 and the lower polarizer 115. The pixel electrode 112 is disposed between the liquid crystal layer 113 and the lower polarizer 115. The common electrode 111 is disposed between the upper polarizer 114 and the liquid crystal layer 113. The common electrode 111 and the pixel electrode 112 are made from transparent material such as indium tin oxide (ITO) or indium zinc oxide (IZO).
A gray level voltage is applied to the pixel electrode 112, and a common voltage is applied to the common electrode 111, thereby a voltage difference is formed between the pixel electrode 112 and the common electrode 111. The voltage difference generates an electric field to control rotations of liquid crystal molecules of the liquid crystal layer 113. Thus, a volume of light transmittance is controlled to display images by the liquid crystal layer 113 together with the upper polarizer 114 and the lower polarizer 115.
The common voltage is generally a constant voltage. However, on one hand, a temperature of the LCD panel 11 varies during a continuous operation. On the other hand, an electrical conductivity of the material of the common electrode 111 is poor. These results a voltage drift phenomenon of the common voltage on the common electrode 111. The voltage drift phenomenon produces flickering and/or viscid images. Therefore, the display performance of the LCD 10 is poor.
What is needed, therefore, is an LCD device that can overcome the above-described deficiencies. What is also needed is a method for driving the LCD device.